Honing mandrels including those that are expandable during honing have been in wide use for a considerable period of time. Such mandrels include open-sided elongated members, rotatable about their axes, with stone assemblies mounted in the open-side of the elongated member and movable radially therein by wedge members which have one or more tapered surfaces along one side which engage a corresponding number of tapered surfaces on the stone assemblies to advance the stone assemblies radially when the wedge moves axially to maintain the stone assemblies engaged, under load, with a work surface being honed. Mandrels of this general character have been in use for a long time. Typical of such mandrels are those shown in Sunnen U.S. Pat. Nos. 2,532,682, 2,580,327, and 3,225,496 and in copending application Ser. No. 07/811,816, filed Dec. 20, 1991 and assigned to Applicant's assignee.
One of the disadvantages or shortcomings of the known mandrel constructions is that the wedge members are usually relatively narrow steel blade-like members with narrow tapered ledges which engage correspondingly narrow beveled surfaces formed on one side of the stone assemblies. Movement of the wedge axially in one direction in the mandrel groove causes the ledges to slidably engage the beveled surfaces on the honing assembly to move the honing assembly radially outwardly. This is done under pressure during honing to maintain engagement between the honing assembly and a work surface. This construction works well and is satisfactory as long as the stone assemblies do not require that a great amount of force be applied to maintain them engaged with the work surface. Also in the known devices the wedge members are relatively loosely positioned in the mandrel groove and no means are provided to prevent the wedges or portions thereof from moving radially in the mandrel grooves. Maintaining the wedges bottomed in their grooves is preferred and is essential if the wedges are also to be used to retract as well as expand the honing diameter of such devices. Typical of the abrasive members or stones used on known honing mandrels are vitrified stones which do a good job of honing for most purposes but are not able to withstand the much greater honing pressures such as are used for honing with relatively harder materials without deteriorating or even crumbling. Also the time required to hone using vitrified abrasives is substantially longer than when honing with harder abrasives such as with superabrasives.
In order to make honing more efficient and faster, honing members or stones of much harder and more wear resistant materials are necessary. These include hones formed using materials that include particles of a substance such as diamond particles and particles of cubic boron nitride. Such materials are able to withstand considerably more honing pressure than vitrified abrasives and are able to hone many more surfaces before they show wear or wear out and need to be replaced or dressed. It has not been practical or economical in the past to mount abrasive members formed of such hard materials onto a conventional mandrel using conventional narrow steel wedge members because the known wedge members are not able to withstand higher honing pressures and Provide sufficient support to make it practical and advantageous to use the harder abrasives. Also, with the known mandrel constructions which for the most part are open-sided along substantially their entire lengths, the openness of the mandrels does not always provide sufficient support for the harder superabrasives without undergoing excessive stress which can cause the mandrels to distort and/or otherwise be damaged.